Spiders, as ectothermic or “cold-blooded” creatures, do not actively generate their own body heat; their internal temperature mirrors that of their surroundings. This means they generally do not “like” or thrive in cold conditions, relying instead on external heat sources to warm themselves. Despite this reliance, many spider species have evolved a variety of strategies to endure and survive the colder months. These adaptations allow them to persist even when temperatures drop significantly.
Spider Biology and Temperature
A spider’s metabolic rate and activity levels are directly influenced by the ambient temperature. As the environment cools, their bodily functions naturally slow down. This reduction in metabolic activity can make them sluggish or even immobile in colder conditions. Spiders, unlike warm-blooded animals, cannot maintain a constant internal temperature, making them highly susceptible to temperature fluctuations. This direct link between external temperature and internal biological processes explains why cold presents a significant challenge to their survival.
How Spiders Survive Cold
Spiders employ a range of physiological and behavioral adaptations to survive cold. Many species produce “antifreeze” compounds, known as cryoprotectants, which lower the freezing point of their bodily fluids. These include substances like glycerol and trehalose, which prevent ice crystal formation within their cells, a process called supercooling. This biochemical mechanism allows some spiders to remain active even at sub-zero temperatures.
Another physiological strategy is diapause, a state of suspended development or metabolic inactivity similar to hibernation. During diapause, spiders significantly reduce their metabolic rate, conserving energy and allowing them to survive extended periods without food. This dormancy helps them endure harsh conditions until warmer weather returns. Behavioral adaptations also involve seeking sheltered microclimates that offer more stable temperatures.
Common Winter Hideouts
Seeking protected locations is a crucial behavioral strategy for spiders during winter, providing insulation from extreme cold. Common natural refuges include spaces under tree bark, within leaf litter, rotting logs, and rock crevices. Some species burrow into soil or snow, finding insulation in the subnivean zone.
Spiders also seek shelter within human structures, utilizing stable indoor environments. Basements, attics, wall voids, crawl spaces, garages, and undisturbed areas like cabinets offer protection, warmer conditions, and access to prey.
When Cold Becomes Lethal
Despite their various survival mechanisms, spiders have temperature thresholds below which they cannot survive. Prolonged exposure beyond their tolerance level can be lethal. For example, brown recluse spiders may die from sustained exposure to 23°F (-5°C) for about 30 days. The formation of ice crystals within a spider’s bodily fluids causes cellular damage, leading to death.
While many spiders are adapted to cold, a sudden or extreme cold snap can significantly impact populations, especially if they haven’t had sufficient time to develop cryoprotectants or find adequate shelter. House spiders, typically accustomed to warmer indoor conditions, may not survive if released outdoors during winter. This highlights the limits of their cold tolerance despite their impressive adaptations.